Abstract. Chemical ozone loss in the Arctic stratosphere
was investigated for the twelve years between 1991 and 2003 employing
the ozone-tracer correlation method. For this method,
the change in the relation between ozone and a
long-lived tracer is considered for all twelve years over the lifetime of the polar
vortex
to calculate chemical ozone loss. Both the accumulated local ozone loss in the lower
stratosphere and the column ozone loss were
derived consistently, mainly on the basis of HALOE satellite observations.
HALOE measurements do not cover the polar region homogeneously over the course
of the winter. Thus, to derive an early winter reference function for each
of the twelve years, all available measurements were additionally used;
for two winters climatological considerations
were necessary. Moreover, a detailed quantification of uncertainties was performed.
This study further demonstrates the interaction between meteorology and
ozone loss. The connection between temperature conditions and chlorine
activation, and in turn,
the connection between chlorine activation and ozone loss,
becomes obvious in the HALOE HCl measurements.
Additionally, the degree of homogeneity of
ozone loss within the vortex was shown to depend on the meteorological conditions.

Results derived here are in general agreement with the results obtained by
other methods for deducing polar ozone loss. Differences occur mainly owing to
different time periods considered
in deriving accumulated ozone loss. However, very strong ozone losses as deduced
from SAOZ for January in winters 1993-1994 and 1995-1996 cannot be identified using
available HALOE observations in the early winter.
In general, strong accumulated ozone loss was found to occur in
conjunction with a strong cold vortex containing a large volume of
possible PSC existence (VPSC),
whereas moderate ozone loss was found if the vortex was less strong and
moderately warm. Hardly any ozone loss was calculated for very warm winters with
small amounts of VPSC during the entire winter.
This study supports the linear relationship between VPSC
and the accumulated
ozone loss reported by Rex et al. (2004) if VPSC was averaged
over the entire winter period. Here, further meteorological factors controlling
ozone loss were additionally identified
if VPSC was averaged over the same time interval as that for which
the accumulated ozone loss was deduced.
A significant difference in ozone loss (of ≈36DU) was found due to the
different duration of solar illumination of the polar vortex of at maximum 4 hours
per day in the observed years. Further, the increased burden of aerosols in the
atmosphere after
the Pinatubo volcanic eruption in 1991 significantly increased the extent of
chemical ozone loss.